In this paper, the authors provide a study of how to design and implement Wireless Sensor Network (WSN) in NS2 (Network Simulator version 2). A Wireless Sensor Network (WSN) consists of a number of sensors which are spatially distributed and are capable of computing, communicating and sensing. NS2 is an event-driven simulation tool that is useful in studying the dynamic nature of computer networks. NS2 provides users with executable command NS which take on input argument, which is the name of a Tool Command Language (TCL) simulation scripting file.